EP1663443A1

EP1663443A1 - Methods for filtering a fluid and device and filter device for carrying out said method

Info

Publication number: EP1663443A1
Application number: EP05773579A
Authority: EP
Inventors: Harald Pohl
Original assignee: Maag Pump Systems Textron GmbH
Current assignee: Maag Pump Systems GmbH
Priority date: 2004-08-19
Filing date: 2005-08-08
Publication date: 2006-06-07
Also published as: WO2006018006A1; US20080217255A1

Abstract

The invention relates to two methods for filtering a fluid, and to a device and filter device for carrying out said method. The fluid to be filtered is conducted through at least one filter (8), wherein the flow of the fluid is throttled (5). At least one real value of a working parameter of the fluid is measured (11). Said real value is compared to a set-point value and at least one manipulated variable is produced according to at least one divergence between the real and set-point values. The degree of throttling (5) is modified in accordance with said manipulated variable.

Description

Method for filtering a fluid, and device and filter device for carrying out the method

The present invention relates to a first method for filtering a fluid, in particular for filtering a polymer melt, with the features of the preamble of patent claim I ₇ a second method for filtering a fluid, in particular for filtering a polymeric melt, with the features of the preamble of patent claim 2, a Vorrich¬ device for carrying out this method with the features of the preamble of claim 8 and a filter device for carrying out the method with the features of the Oberbe¬ handle of claim 25th

In order to process fluids, in particular polymeric melts, it is known to filter these fluids or polymeric melts. Here, a pressurized stream of fluid is continuously guided through a filter, so that accordingly the thus filtered fluid can be supplied to a tool. By way of example, reference is made here only to the extensive prior art to DE 44 08 803, DE 196 12 790 and DE 195 19 519, which, like the present application, preferably describe the filtration of polymeric melts.

In the known methods, with increasing degree of contamination of the filter, the pressure prevailing upstream of the filter increases constantly, so that when a pressure limit value, which is usually not measured, is reached, a continuous or discontinuously carried out filter change must take place. As a rule, this filter change is carried out according to empirically determined time sequences, the filtration process not being interrupted during the continuous filter change, while in the case of a discontinuous filter change, an interruption and an exchange or a cleaning of the filter takes place here.

The previously known methods have the disadvantage that the fluid to be filtered in each case is subject to a cyclical pressure fluctuation resulting from a first, pressure-increasing partial cycle, caused by the increasing contamination of the filter, possibly a second, generally quite short expiring sub-cycle further increasing the pressure, caused by the replacement or cleaning of the filter, and a third subcycle composed, wherein at the beginning of this third Teilzyklusses a pressure level upstream of the filter is achieved, which speaks ent the initial pressure level of the first sub-cycle , This initial pressure level of the third subcycle is due to the fact that a fresh, i. unloaded filter due to the cleaning of the filter or the replacement of the same is then again available for further filtration, this unloaded filter is loaded again in carrying out the further filtration process again with dirt, as described above for the first subcycle.

The previously described, cyclically occurring pressure fluctuations upstream of the filter can, depending on the respective fluid to be filtered and in particular depending on the respective polymer melt to be filtered, lead to undesired changes in the system to be filtered. Thus, especially with sensitive polymeric melts, i. of such melts, which change their chemical and / or physical properties depending on the prevailing pressure, undesirable production errors occur.

The present invention is based on the object of providing a first method, a second method, a device and a filter device for carrying out the method, which provide particularly gentle filtration of a Fluids, in particular a particularly gentle filtration of a polymeric melt allow.

This object is achieved by a first method having the characterizing features of patent claim 1, by a second method having the characterizing features of patent claim 2, by a device having the characterizing features of claim 8 and by a filter device having the ident ¬ drawing features of claim 25 solved.

The inventive method for filtering a fluid, in particular for filtering a polymeric melt, provides that a pressurized stream of the fluid is continuously passed through at least one filter and thereafter the thus filtered fluid is supplied to a tool, as well as at the beginning of the prior art also the case. In contrast to this prior art, however, in the first method according to the invention, the flow of the filtered fluid and / or the flow of the filtered fluid is throttled, with at least one actual value of a working parameter of the fluid being measured. Furthermore, in the method according to the invention, the actual value is compared with a predefinable, ie thus adjustable, setpoint value, so that at least one manipulated variable is generated as a function of at least one actual setpoint value deviation. Depending on this manipulated variable, the degree of throttling is then changed in the method according to the invention. In other words, therefore, the first method according to the invention is based on the one hand in the fluid flow at least one throttle is arranged, which is po¬ sitioned either upstream of the filter, downstream of the filter or upstream and downstream of the filter in the fluid stream and on the other hand, the degree of throttling gesteu¬ ert, wherein for this control the actual value of a Arbeits¬ parameters of the fluid measured and this measured actual value of the fluid is compared with a predetermined target value, so that then at an actual target value deviation the for the controller required manipulated variable is generated by which the opening degree of the throttle is changed.

The inventive method has a number of advantages. Thus, it should first be noted that the time of filter change is not determined empirically by the method according to the invention, as in the known method, but this time is determined exactly on the basis of measured values recorded. This makes it possible that a filtration of the fluid carried out according to the method according to the invention is made particularly reproducible, so that accordingly the inventive device can be operated with a reduced personnel expenditure, without unwanted downtime occurring auf¬. Due to the fact that in the method according to the invention, in addition to the at least one filter which is increasingly loaded with dirt in the course of use, whereby the pressure upstream of the filter changes in the fluid to be filtered, there is also a throttle which also generates a backpressure ¬ is the whose opening degree and thus also their back pressure ver¬ changeable and is particularly adaptable, can be compensated in the inventive method caused by the increasing Filterver¬ pollution increasing pressure upstream of the filter by increasing the opening degree of the throttle so that the inventive method a pressure-constant Filtra¬ tion of the fluid while maintaining a constant Men¬ genstromes of filtered fluid per unit time to the tool and / or while maintaining a constant temperature and / or a constant viscosity. In this case, in particular the process according to the invention allows this pressure constant to prevail upstream of the filter, whereby undesirable chemical and / or physical property changes of the polymer melt are preferably avoided in the case of pressure-sensitive polymeric melts. This constant pressure, which is present in particular upstream of the filter in the method according to the invention, further protects the device positioned there for generating the pressurized flow of the fluid, wherein it is This is preferably an extruder, a corresponding pump or a pressurized fluid supply. Moreover, the pressure constancy provided in the process according to the invention causes the gases which are often contained in the fluid to be filtered, which are to be removed before the filtration process, to be let off at one and the same point upstream of the filter, which in the known methods because of the previously described printing cycles is not the case. As a result, the fluid to be filtered, which is preferably a polymeric melt, is degassed optimally, which has a considerable positive influence on the quality of the workpiece produced by the tool, so that by applying the method according to the invention not only improved workpieces (extrudates) can be produced but also the rate of defective workpieces is reduced.

For clarity, it should be noted that the term fluid used in the present application covers in particular a polymeric melt, preferred examples of such a polymeric melt being the plastics polypropylene, polyethylene, high-pressure polypropylene, low-density polyethylene, linear low-density polyethylene, polystyrene, polyamide, alkyl Butadiene-styrene (ABS), polyester, polyoxymethylene (POM), polyacrylates, in particular polymethyl methacrylates (PMMA) and polyvinyl chloride. Furthermore, it should be pointed out that all terms used in the singular, such as the "filter" in the present application not only the one term, for example, a single filter includes, but that this includes any be¬ arbitrary number these terms, such as any number of filters, falls. It should also be noted that all terms associated with "and / or" are to be construed both as additive and as an alternative, and this statement also applies if only the last two terms are used with a list of more than two terms with "and / or "are connected, so that in this type of enumeration all terms or only a part of the concepts additively or alternatively linked together are. The terms upstream and downstream always refer to the flow direction of the fluid to be filtered.

A basically second method according to the invention for filtering a fluid, in particular for filtering a polymer melt, provides that a pressurized stream of the fluid is continuously passed through at least one filter and thereafter the thus filtered fluid is supplied to a tool. As in the case of the first method according to the invention described above, in the second method according to the invention the flow of the fluid to be filtered and / or the filtered fluid is throttled, but in the case of the second method according to the invention the actual value of the degree of throttling is preset to one A value is set. Furthermore, in this second method according to the invention, an actual value of a working parameter of the fluid is measured and the actual value of the degree of throttling is changed until the abovementioned actual value of the working parameter of the fluid assumes an input and constant desired value , This second process according to the invention, like the first process according to the invention, fulfills the above-mentioned object and has all the advantages as already described above for the first process according to the invention. This second method according to the invention differs from the first method according to the invention in that in this case the degree of throttle is specified, that an actual value of a parameter of the fluid is measured and that the actual value of the degree of throttling is changed until the actual value of the working parameter of the fluid assumes an input and constant setpoint value, so that this second embodiment of the method according to the invention also makes possible a reproducible and pressure-constant filtration of the fluid.

In other words, in the second method according to the invention described above, the degree of throttling is set and changed until the actual value of the working parameter assumes a constant, input desired value, wherein In the course of the filtration process and with increasing contamination of the filter, this tuning is constantly repeated and adapted accordingly.

With regard to the actual value of the working parameter of the fluid which is to be measured in the method according to the invention, it is generally to be stated that any measuring method and thus any measured value is suitable for this purpose, which also changes when the degree of contamination of the filter changes. In particular, in the method according to the invention, the actual value of the working parameter of the fluid is measured by the pressure, the flow rate, the flow rate, the temperature and / or the viscosity of the fluid to be filtered and / or of the filtered fluid.

As already explained in the beginning of the method according to the invention, in the method according to the invention the flow of the fluid is throttled depending on the degree of contamination of the filter and / or the number of filters available for the filtration, the degree, i. the size, this throttle - generally speaking - depends on how the measured actual value of a working parameter of the fluid changes with regard to an adjustable desired value of the fluid.

If a highly contaminated fluid, for example a polymeric melt of a recycle material, is to be filtered by the process according to the invention, it is appropriate that an embodiment of the process according to the invention is used in which the flow of the filtered fluid is throttled ge. This embodiment of the method according to the invention has the advantage that the throttle, which is in this case arranged downstream of the filter, can not be so easily contaminated, since the relevant throttle element comes into contact only with filtered fluid.

However, if the fluid to be filtered only slightly contaminated, sees another embodiment of the method according to the invention in that the throttle is arranged upstream of the filter, so that, accordingly, the flow of the fluid to be filtered is throttled ge.

A particularly suitable embodiment of the method according to the invention, which is to be carried out without interference, provides that in this embodiment the pressure of the fluid to be filtered is measured as the actual value of the working parameter of the fluid, so that when a predetermined pressure value is exceeded, that in the above sense is denoted as set value, the degree of Drosse¬ ment is reduced and that falls below a predetermined pressure value nen the degree of throttling is increased. In other words, in this preferred embodiment, the degree of throttling is thus changed depending on the pressure prevailing upstream of the filter in such a way that there is a filter at the beginning of the filtration in which a filter not loaded with dirt or only slightly loaded is present and accordingly the pressure relatively low value, high throttling takes place. With increasing contamination of the filter, which leads to an increase in pressure upstream of the filter, the degree of throttling is verrin¬ siege, which means that the throttle further opens and the pressure is lowered and maintained at a constant pressure , In the final state of this operation, in which the filter is considerably contaminated and an exchange or cleaning of the filter is required, the degree of throttling is then reduced so that the throttle has almost no or no influence on the fluid flow. Then, when then a filter unloaded with dirt is available again, the degree of throttling is increased, so that at this time upstream of the filter again, prevails, prevailing over the entire cycle constant initial pressure. By tuning the changing degree of contamination of the filter and the opening degree of the throttle is thus particularly simple and advantageous in this embodiment of the method er¬ sufficient that always upstream of the filter constant, only in¬ nerhalb low pressure fluctuations varying pressure value lies. At the same time, it is ensured that the tool arranged downstream of the filter is supplied with a volume or mass flow of the filtered fluid which is constant over time.

In another development of the special embodiment of the method according to the invention described above, not only the pressure of the fluid upstream of the filter but also the pressure of the fluid downstream of the restriction is measured, in which case a signal for the Performing a filter change is generated. In this case, this filter change, which is equivalent to a genuine replacement of the filter or for a cleaning of the filter, be performed either manually or automatically, in the first case then preferably an optical or acoustic signal indicating the need for der¬ like filter change. The particular advantage of this embodiment of the method according to the invention can be seen in the fact that not only the previously described pressure-constant filtration is made possible but at the same time an¬ is shown when a manual or automatic filter change is required. By applying this special embodiment of the method according to the invention, considerable personnel capacities can thus be saved and the time of the filter change can be exactly quantified.

The present invention furthermore relates to a device for carrying out the method according to the invention described above.

The device according to the invention has a device, in particular an extruder, for producing a continuous stream of a pressurized fluid, in particular a polymer melt. This is followed, viewed in the flow direction of the fluid to be filtered, by a filter device which has at least one filter for filtering the fluid. has, so that the fluid is filtered by this filter means. At least one tool follows this filter device in the device according to the invention. Furthermore, in the device according to the invention, a detection device for the actual value of a working parameter of the fluid is assigned to the region upstream and / or downstream of the filter device, wherein upstream and / or downstream of the filter device a throttle is also provided in the flow of the fluid. In the event of a deviation of the actual value of the working parameter of the fluid from a prescribable, ie adjustable, desired value of the working parameter of the fluid, the detection device generates a manipulated variable for varying the opening degree of the throttle, such that the contamination of the reactor increases at least one filter, the degree of opening of the throttle is continuously increased. In other words, the device according to the invention essentially differs from the known devices in that in the device according to the invention a throttle is arranged in the flow path of the fluid whose degree of opening depends on a detected and with a predetermined value of the fluid ver¬ Value is varied such that with increasing Ver¬ pollution of the filter, the opening degree of the throttle is increased, while at the beginning of the filtration, ie at a time when the filter is not dirty, the opening degree of the throttle is low, so that accordingly this throttle opposes the fluid flow with a corresponding resistance. Of course, the device according to the invention ensures that, irrespective of the degree of contamination of the filter and the opening degree of the throttle, a constant amount of fluid per unit time is supplied to the tool provided downstream of the filter device over the entire period.

The device according to the invention has all the advantages listed above for the method according to the invention. It should also be noted here that in the device according to the invention the time of the filter change is not determined empirically, as in the known devices, but instead that this time is determined exactly on the basis of detected measured values. As a result, not only is the filtration of the fluid to be carried out by means of the device according to the invention made particularly re-producible, but the device according to the invention can also be operated with a reduced personnel expenditure, without unwanted downtimes or interruptions occurring. Due to the fact that in the device according to the invention in addition to the filter, which is increasingly loaded with dirt in the course of use, whereby the pressure upstream of the filter in the fluid to be filtered, yet another, a back pressure generating throttle is present, the Opening degree and thus also their back pressure verän¬ derable and is particularly adaptable, can be in the inventive device, the rising pressure upstream of the filter by increasing the opening degree of the throttle compensate, so that the device according to the invention a pressure-constant Fil¬ tration of the fluid while maintaining a constant Vo¬ lumenstromes of filtered fluid per unit time to the tool allows. In particular, the device according to the invention allows this constant pressure to prevail upstream of the filter, whereby undesirable chemical and / or physical property changes of the polymer melt are preferably avoided in the case of pressure-sensitive polymeric melts. This constant pressure, which is preferably present upstream of the filter in the device according to the invention, moreover protects the devices positioned there for generating the pressurized flow of the fluid, in particular an extruder, a corresponding pump or a pressurized one standing fluid supply is. Furthermore, the pressure constancy present in the device according to the invention has the effect that often gases to be removed in the fluid to be filtered, which are to be removed before the filtration process, can be discharged at one and the same point upstream of the filter, which in the known devices the previously described printing cycles are not or only very expensive the case. As a result, the fluid to be filtered, in which it is preferably is a polymeric melt, optimally degassed, which has a significant positive influence on the quality of the workpiece produced by the tool, so that not only improved workpieces can be produced by the inventive device but also the rate of defective workpieces is reduced.

As already stated above in the method according to the invention, in the device according to the invention, the detection device is designed in such a way that the detection device detects as the actual value of the working parameter of the fluid such a measured value which changes when the degree of contamination of the Filters also changes. In particular, the detection device provided in the device according to the invention is designed such that it detects the actual value of the working parameter of the fluid pressure, the flow rate, the Durchflußgeschwin¬ speed, the temperature and / or the viscosity of the fluid.

A preferred embodiment of the Vorrich¬ device according to the invention provides that the detection device auf¬ has a pressure sensor for detecting the fluid pressure upstream or downstream or upstream and downstream of the filter device, wherein in the first two cases in which the fluid pressure upstream or downstream of the Filter device er¬ is taken, a pressure and in the latter case (upstream and downstream) a differential pressure is measured. Furthermore, the Erfas¬ sungseinrichtung is designed so that the so as Arbeitsparame¬ ter of the fluid detected pressure actual value or the differential pressure actual value with the predetermined, ie adjustable, desired pressure value or differential pressure target value is compared and that so¬ soon the actual value exceeds the setpoint value, a manipulated variable is generated er¬ which causes an increase in the opening degree of the throttle. This embodiment of the device according to the invention has the decisive advantage that in this way in a particularly simple and reproducible manner, in particular the pressure can be kept constant upstream of the filter device, it being noted as an additional advantage of this embodiment of the device according to the invention that the here vorgese¬ Henen pressure sensors are inexpensive and are characterized by a low maintenance and störunanfällige mode of operation.

Another embodiment of the device according to the invention comprises such a detection device which is provided with at least one temperature sensor for detecting the fluid temperature upstream and / or downstream of the filter device or for Erfas¬ solution of a differential temperature. The temperature actual value of the fluid or the difference temperature actual value determined in this way is compared in the detection device with the predeterminable temperature setpoint value or predefinable difference temperature setpoint value, so that as soon as the Actual value exceeds the setpoint value, a manipulated variable is generated by the detection device, which causes an increase in the opening degree of the throttle. This embodiment of the device according to the invention is preferably used when the device according to the invention a thin liquid polymer melt is to be filtered.

A particularly advantageous development of the device according to the invention provides that in this case the throttle is arranged upstream of the filter device. This embodiment is always preferably used when the fluid to be filtered has only a relatively low degree of contamination, so that there is no danger here that the functionality of the throttle is impaired by deposited dirt particles.

In a further development of the previously described embodiment of the device according to the invention, the throttle, which is arranged upstream of the filter device, associated with a valve or this valve is integrally formed with the throttle, said valve in its open position, a fluid flow to the atmosphere derived. This embodiment of the inventive The device is always preferably used when the respective fluid to be filtered, in particular the polymer melt to be filtered, tends to form particulate agglomerates even at short standstill times. These particle-shaped agglomerates can then be removed from the device according to the invention by means of the valve at the beginning of the filtration, so that these agglomerates do not contaminate the filter at the beginning of the filtration.

Another embodiment of the device according to the invention provides that in this case the throttle is arranged downstream of the filter device. This embodiment of the device according to the invention is always used when the fluid to be filtered is heavily contaminated, the advantage of such an arrangement of the throttle being that the throttle provided downstream of the filter device does not come into contact with contaminated fluid , Furthermore, this embodiment of the device according to the invention is distinguished by a high degree of operational reliability, so that it is preferably also used for filtering polymeric recycling material melts.

A particularly fine tuning of the degree of throttling of the fluid flow is achieved in the apparatus according to the invention in that upstream and downstream of the filter device in each case a throttle is provided. In particular, when the throttle arranged on the filter device is provided with the previously described valve or this throttle is associated with the previously described valve, a dermar¬ term embodiment of the device according to the invention can be heavily soiled polymeric melts, less polluted polymers Melting and also melting such melts tend to form solid agglomerates, so that depending on the respective contamination of the polymer melt to be filtered or its properties, in the case of heavily soiled polymer melt, preferably only those arranged downstream of the filter device Throttle, with less heavily soiled melt both throttles together or individually a throttle is set ein¬, while in those melts which tend to form agglomerates, additionally arranged upstream of the Fil¬ tereinrichtung throttle for discharging the agglomerates at the beginning of a filtration can be used. Thus, this embodiment of the device according to the invention is universally applicable and very easily adaptable to the respective requirements.

With regard to the throttle provided in the device according to the invention in the fluid flow, it is generally to be noted that this throttle is designed so that its degree of opening is to be changed within narrow limits and that, furthermore, the throttle is designed such that dead spaces are minimized.

A particularly störunanfällige embodiment of erfindungsge¬ MAESSEN device has a throttle, which is provided with a through-flow of the fluid receiving space. This receiving space is preferably a pipe section through which the fluid flows, this receiving chamber having a throttle element penetrating into the fluid. Here, the throttle element between a first position in which the fluid stream is almost interrupted, so that there is a low Öff¬ tion of the throttle, and a second position in which the fluid flow through the throttle element is not or almost not hindered, so that there is a high degree of opening of the throttle, and vice versa, movable. In the simplest case, in this embodiment of the device according to the invention Vor¬ the throttle element is designed as a flat slide and a pipe section through which the fluid flows, assigned, so that the degree of Öff¬ opening of the throttle is adjustable by a movement of this flat slide.

A further development of the previously described embodiment of the device according to the invention provides a throttle in which the throttle element as a cylindrical throttle piston and the receiving space are formed as a cylindrical receiving space, wherein the flow of fluid is passed through this cylindrical Auf¬ receiving space. The cylindrical throttle piston is axially displaceably mounted in the cylindrical receiving space between the previously described first position and the second position, so that the degree of opening of the throttle can be changed as desired by an axial displacement of the cylindric throttle element. Instead of the cylindrical receiving space, a pipe section, through which the fluid is guided, can serve as a receiving space, this pipe section then having a correspondingly shaped housing area for guiding and holding the cylindrical throttle element. In the case of an axial displacement of the cylindrical throttle element whose diameter is greater than the cross section of the pipe section, the throttle element then penetrates into the receiving space designed as a pipe section and then, depending on its penetration depth, effects the desired throttling of the fluid flow. Alternatively, however, it is also possible to use a cylindrical throttle element which is provided with a passage opening corresponding to the cross section of the pipe section, preferably a cylindrical throughbore, wherein this throttle is mounted in a housing section such that an axial displacement of the housing cylindrical throttle element, the passage opening provided therein more or less fluch¬ with the pipe inner wall, whereby the degree of opening of the throttle is particularly easy and accurate adjustable.

Another embodiment of the device according to the invention provides that this has a specially shaped throttle, with this throttle is highlighted by the fact that it completely avoids Strömungs¬ dead zones. In order to achieve this, the throttle has a conically formed receiving space, whereby within this receiving space there is arranged a likewise adapted throttle element which is adapted thereto. Here, the conical throttle element between the first position and the second position is axially displaceable, wherein the receiving space a upstream of the throttle element arranged fluid supply part channel and a downstream of the throttle element provided Fluidabfuhr- partial channel are assigned. The flow of the fluid in the receiving space and via the fluid discharge sub-channel is removed from the receiving space via the fluid supply sub-channel. Due to the conicity of the receiving space and the throttle element, this configuration of the throttle allows a very fine adjustment of the opening degree of the throttle, at the same time preventing the conical walls of the receiving space and the throttle unwanted deposition of fluid residues.

In particular, when in the above-described embodiment of the device according to the invention, which has a special Dros¬ sel, the fluid removal part channel has a seen in Strömungsrich¬ direction of the fluid first portion which ver¬ on both sides of the housing of the receiving space ver¬ runs and which opens into the fluid discharge part channel, the previously mentioned advantages are achieved to a particularly high degree by a choke configured in this way.

In particular, the first portion of the Fluidabfuhrteilkanals seen in the flow direction of the fluid as an annular channel ausgebil¬ det, the annular channel partially or completely enclosing the housing of the receiving space from the outside, as will be explained below with reference to a specific embodiment.

In order to bring about the desired flow of the fluid flow in the device according to the invention, depending on the respective charge of the filter, it is advisable that the throttle element of the previously described embodiment is moved as a function of the manipulated variable generated by the detection device. This movement, which preferably represents an axial displacement of the throttle element, can be effected either manually or preferably automatically, for which purpose a drive for the axial movement of the same is assigned to the throttle element. is orders. This drive is designed in particular as a hydraulic, pneumatic or electric drive.

A development of the previously described embodiment of the device according to the invention provides that the throttle element is moved only over a predetermined size and preferably displaced axially. This predetermined size lies between the first and second position of the throttle element, so that accordingly the opening degree of the throttle is increased or reduced. When exceeding this predetermined size, an optical and / or acoustic signal is generated, so that when this signal occurs the operator is displayed that a filter change is required.

A further embodiment of the previously described embodiment of the device according to the invention provides that, when the predetermined size is exceeded, backwashing of a contaminated filter is automatically triggered. However, this embodiment of the device according to the invention requires at least two filters, these two filters optionally having a first position in which they both filter the fluid flow and in a second position in which one filter filters the fluid flow while the other one Filter with a partial flow of filtered fluid opposite to the flow direction during filtration is backwashed, are movable. During this backwashing process, the partial flow of filtered fluid then dissolves the contaminants accumulated on the filter surface and, opposite to the flow direction of the fluid during filtration, leads it to the atmosphere via a suitable valve upstream of the filter device, so that after completion of this backwashing process, a flow of Dirt-depleted filter for re-filtration is provided again.

In principle, the device according to the invention may comprise all filter devices known per se, in which case the band filters described in the prior art can be used as examples. are. However, it is particularly suitable if the device according to the invention comprises a filter device which has at least two filters arranged at an axial distance from one another within a bolt mounted in a housing and axially displaceable for this purpose. Alternatively, the at least two filters can be flowed through with the fluid to be filtered or at least one filter is flowed through with the fluid to be filtered, while at the same time the at least one other filter is in a position outside the filter device, so that this one, filters located outside the filter device can be manually replaced by the respective operating personnel and cleaned or replaced and replaced by a new filter.

Another, likewise advantageous embodiment of the device according to the invention comprises a filter device which has two bolts arranged inside a housing and axially displaceable for this purpose, each being provided with at least two filters arranged at an axial distance from each other. In this case, these bolts are mounted in corresponding housing bores in a fluid-tight and axially displaceable manner, whereby optionally all filters are flowed through by the fluid to be filtered or at least one filter is located in a position outside the filter device, while the remaining other filters are separated from the filter the fluid to be filtered flows through it. This ensures that, without interrupting the filtration process, one or more filters which are or are located in a position outside the filter device can be exchanged or cleaned, without an undesired pressure fluctuation occurring in the process.

The present invention further relates to a filter device for carrying out the method according to the invention.

The filter device according to the invention has a first An¬ circuit element for connecting the filter device with a Device, in particular with an extruder, for generating ei¬ nes continuous flow of a pressurized fluid, in particular a polymeric melt on. Furthermore, a second connecting element is provided, which connects the filter device according to the invention with a tool, wherein the inventive filter device comprises at least one filter through which fluid flows. Furthermore, in the filter device according to the invention, a detection device for the actual value of a working parameter of the fluid is arranged between the first connection element and the filter and / or between the filter and the second connection element, upstream and / or downstream of the filter device, ie Thus, between the first connection element and the filter and / or between the filter and the second connection element, further provided in the flow of the fluid, a throttle. In the case of a deviation of the actual value of the working parameter of the fluid from a predefinable, ie adjustable, desired value of the working parameter of the fluid, the detection device generates a manipulated variable for changing the opening degree of the throttle, such that with increasing contamination of the at least one Filters the degree of opening of the throttle is increased continuously. In other words, the filter device according to the invention essentially differs from the known devices in that a throttle in the flow path of the fluid upstream and / or downstream of the filter is arranged in the filter device according to the invention, whose degree of opening depends on a detected and compared with a predetermined value of the fluid value is varied such that with increasing contamination of the filter, the opening degree of the throttle is increased, while at the beginning of the filtration, ie at a time when the filter is not dirty, the opening degree of the Throttle is low, so that accordingly this throttle the fluid flow ent speaking resistance (back pressure) opposes. Of course, the filter device according to the invention ensures that, regardless of the degree of contamination of the filter and the degree of opening of the throttle, a per Time unit constant amount of fluid is supplied to the tool provided downstream of the Filtereinrich¬.

The filter device according to the invention has all the advantages listed above for the method according to the invention and the device according to the invention. Thus, it should also be noted here that in the filter device according to the invention the time of the filter change is not determined empirically, as in the case of the known devices, but that this point in time is determined exactly on the basis of detected measured values. In this way, not only is the filtration of the fluid to be carried out by means of the filter device according to the invention made particularly reproducible, but the filter device according to the invention can also be operated with reduced personnel expenditure without undesirable downtimes or interruptions occurring. Due to the fact that in the inventive filter device in addition to the filter, which is increasingly loaded with dirt in the course of use, whereby the pressure upstream of the filter in the fluid to be filtered än¬ changed, nor a likewise, a back pressure generating throttle is present, whose opening degree and thus their Ge gy pressure changeable and is particularly adaptable, can be compensated in the filter device according to the invention, the rising pressure upstream of the filter by increasing the degree of opening of Dros¬ sel, so that the filter device according to the invention a pressure-constant filtration of the fluid while maintaining ei¬ nes a constant volume flow of filtered fluid per unit time to the tool allows. In particular, the filter device according to the invention permits this pressure consistency to prevail upstream of the filter, whereby undesirable chemical and / or physical property changes of the polymer melt are preferably avoided in the case of pressure-sensitive polymeric melts. This constant pressure, which is preferably present upstream of the filter in the filter device according to the invention, further protects the devices positioned there for generating the pressurized flow of the device Fluids, which is in particular an extruder, a corresponding pump or a pressurized fluid reservoir. Furthermore, the pressure constancy present in the filter device according to the invention causes gases which are often to be removed in the fluid to be filtered, which are to be removed before the filtration process, to be discharged at one and the same point upstream of the filter, which is known in the art Devices because of the Druckzy¬ initially described Klen not or only very expensive the case. As a result, the fluid to be filtered, which is preferably a polymeric melt, is optimally degassed, which has a considerable positive influence on the quality of the workpiece produced by the tool, so that not only improved workpieces are produced by the filter device according to the invention but also the rate of defective workpieces is reduced. Due to the compactness of the filter device according to the invention can be installed in the context of a retrofit kit in any conventional fluid filtration device.

As already explained in the beginning of the method according to the invention, in the filter device according to the invention, the detection device is designed such that the detection device detects such a measured value as the actual value of the working parameter of the fluid, which also changes when the degree of contamination of the filter is changed changes. In particular, the detection device provided in the filter device according to the invention is designed such that it detects the pressure, the flow rate, the flow rate, the temperature and / or the viscosity of the fluid as the actual value of the working parameter of the fluid.

A preferred embodiment of the invention Filterein¬ direction provides that the filter device associated detection device each having a pressure sensor for detecting the fluid pressure upstream or downstream or upstream and downstream of the filter device, wherein in the first mentioned In both cases, in which the fluid pressure is detected upstream or downstream of the filter device, a pressure and in the latter case (upstream and downstream), a differential pressure is measured. Deswei¬ teren the detection device is designed so that the thus detected as working parameters of the fluid pressure-actual value or the differential pressure-actual value with the predetermined, ie adjustable, desired pressure value or differential pressure target value is compared and that as soon as the actual value exceeds the setpoint value, a manipulated variable is generated, which causes an increase in the Öffnungsgra¬ of the throttle. This embodiment of the filter device according to the invention has the decisive advantage that in this way the pressure upstream of the filter device can be kept constant in a particularly simple and reproducible manner, as an additional advantage of this embodiment of the filter device according to the invention Here provided pressure sensor are inexpensive and are characterized by a low maintenance and störunanfällige Betriebs¬ wise.

Another embodiment of the inventive filter device has such a detection device which is provided with at least one temperature sensor for detecting the fluid temperature upstream and / or downstream of the filter device or for detecting a differential temperature. The temperature actual value of the fluid or the difference temperature actual value detected thereby is compared in the detection device with the predeterminable temperature set value or predefinable difference temperature set value, so that as soon as the actual value Value exceeds the setpoint value, a manipulated variable is generated by the detection device, which causes an increase in the opening degree of the throttle. This embodiment of the filter device according to the invention is preferably used when a low-viscosity polymeric melt is to be filtered with the filter device according to the invention. A particularly advantageous development of the filter device according to the invention provides that in this case the throttle is arranged upstream of the filter device between the first closure element and the filter. This embodiment is always preferably used when the fluid to be filtered has only a relatively low degree of contamination, so that in this case there is no risk that the functioning of the throttle is affected by deposited dirt particles.

In a further development of the previously described embodiment of the filter device according to the invention, the throttle, which is arranged upstream of the filter device, assigns a valve or this valve is formed integrally with the throttle, whereby this valve in its open position directs a fluid flow towards the atmosphere derives. This embodiment of the filter device according to the invention is preferably always used when the fluid to be filtered in each case, in particular the polymer melt to be filtered, tends to form particulate agglomerates even during short standstill times. These particulate agglomerates can then be removed by means of the valve at the beginning of the filtration of the fluid, so that these agglomerates do not contaminate the filter even then.

Another embodiment of the filter device according to the invention provides that in this case the throttle is arranged downstream of the filter device. This embodiment of the erfindungsge¬ MAESSEN filter device is always applied when the fluid to be filtered is heavily contaminated, the additional advantage of such an arrangement of the throttle is seen in the fact that the throttle provided downstream of the filter device does not come into contact with contaminated fluid. Furthermore, this embodiment of the filter device according to the invention is characterized by a high level of operational reliability, so that it is preferably also used for the filtration of polymeric recycled material melt. A particularly fine tuning of the degree of throttling of the fluid flow is achieved in the filter device according to the invention characterized in that upstream and downstream of the filter in each case a throttle is provided. In particular, when the throttle arranged on the filter is provided with the above-described valve or this valve is associated with the previously described valve, strongly contaminated polymeric melts, less soiled polymers, can be obtained with such an embodiment of the filter device according to the invention Melting and also melting such melts tend to form solid agglomerates, so that depending on the respective contamination of the polymer melt to be filtered or its properties then, in the case of heavily soiled polymer melt, preferably only the throttle arranged downstream of the filter, in the case of less heavily soiled melts, both throttles together or individually a throttle is used, while in those melts which tend to form agglomerates, additionally the throttle arranged upstream of the filters for discharging the agglomerates at the beginning of a filtration can be used. Thus, this embodiment of the inventive filter device is universally applicable and very easily adaptable to the respective requirements.

By way of clarification, it should be noted that the designation upstream of the filter determines a position which lies between the first connection element and the filter, and that the designation downstream of the filter determines a position which lies between the filter and the second connection element.

With regard to the throttle provided in the filter device according to the invention in the fluid flow is generally noted that this throttle is designed so that their degree of opening within half confine narrow limits and that further the throttle is designed so that dead spaces are minimized. A particularly störunanfällige embodiment of the erfindungsge¬ MAESSEN filter device has a throttle, which is provided with a through-flow of the fluid receiving space. This receiving space is preferably a pipe section through which the fluid flows, this receiving chamber having a throttle element penetrating into the fluid. Here, the throttle element is • between a first position in which the fluid flow is almost interrupted, so that there is a low Öff¬ tion of the throttle, and a second position in which the fluid flow through the throttle element is not or almost not hindered , So that there is a high degree of opening of the throttle, and vice versa, movable. In the simplest case, in this embodiment of the filter device according to the invention, the throttle element is designed as a flat slide and associated with a pipe section through which the fluid flows, so that the degree of opening of the throttle can be adjusted by a movement of this flat slide.

A further development of the above-described embodiment of the filter device according to the invention provides a throttle, in which the throttle element is designed as a cylindrical throttle piston and the receiving space as a cylindrical receiving space, wherein the flow of fluid is passed through this cylindrical Auf¬ receiving space. The cylindrical throttle piston is axially displaceably mounted in the cylindrical receiving space between the previously described first position and the second position, so that the degree of opening of the throttle can be changed as desired by an axial displacement of the cylindric throttle element. Instead of the cylindrical receiving space and a pipe section through which the fluid is guided, serve as a receiving space, said pipe section then has a correspondingly shaped housing portion for guiding and holding the cylindrical throttle element. In the case of an axial displacement of the cylindrical throttle element, the diameter of which is greater than the cross section of the pipe section, the throttle element then penetrates into the structure formed as a pipe section. and then causes, depending on its penetration depth, the desired throttling of the fluid flow. Alternatively, however, it is also possible to use a cylindrical throttle element which is provided with a passage opening corresponding to the cross section of the pipe section, preferably a cylindrical throughbore, wherein this throttle is mounted in a housing section such that an axial displacement of the housing cylindrical throttle element, the passage opening provided therein more or less fluch¬ with the pipe inner wall, whereby the degree of opening of the throttle is particularly easy and accurate adjustable.

Another embodiment of the filter device according to the invention provides that it has a specially shaped throttle, whereby this throttle is distinguished by the fact that it completely avoids flow dead zones. To achieve this, the throttle has a conical receiving space, wherein within this receiving space a thereto adapted, also conical ausgestaltetes throttle element is arranged. In this case, the conical throttle element is axially displaceable between the first position and the second position, wherein a fluid supply subchannel arranged upstream of the throttle element and a fluid discharge subchannel provided downstream of the throttle element are assigned to the receiving space. The flow of the fluid in the receiving space and via the fluid discharge subchannel is removed from the receiving space via the fluid supply sub-channel. Due to the Koni¬ capacity of the receiving space and the throttle element allows this configuration of the throttle a very fine setting of Öff¬ tion of the throttle, at the same time the conical Wan¬ tions of the receiving space and the throttle prevents unwanted Ab¬ storage of fluid residues.

In particular, in the case of the previously described embodiment of the filter device according to the invention, which has a special throttle, the fluid removal part passage has a first section, viewed in the flow direction of the fluid, which On both sides of the housing of the receiving space runs outside the same and which opens into the fluid discharge part channel, the previously mentioned advantages are achieved to a particularly high degree by a choke designed in this way.

For the above-described embodiments of the inventive filter devices, it should be noted that the fluid supply partial passage is preferably then provided with the first connection element and the fluid discharge part passage with the second connection element.

In order to bring about the desired throttling of the fluid flow in the filter device according to the invention, depending on the respective loading of the filter, it makes sense that the throttle element of the embodiment described above is moved depending on the manipulated variable generated by the detection device. This movement, which preferably represents an axial displacement of the throttle element, can be brought about either manually or preferably automatically, with a drive for the axial movement of the throttle element being assigned to it for the throttle element. This drive is designed in particular as a hydraulic, pneumatic or electric drive.

A further development of the previously described embodiment of the filter device according to the invention provides that the throttle element is moved only over a predetermined size and is preferably displaced axially. This predetermined size is between the first and second position of the throttle element, so that accordingly increases the degree of opening of the throttle or is reduced. When this predetermined size is exceeded, an optical and / or acoustic signal is generated, so that upon occurrence of this signal, the operating personnel are shown that a filter change is required.

A further embodiment of the previously described embodiment of the filter device according to the invention provides that rewinding of a contaminated filter is automatically triggered when the predetermined size is exceeded. However, this embodiment of the inventive filter device requires at least two filters, these two filters optionally having a first position in which they both filter the fluid flow and a second position in which one filter filters the fluid flow while the other one Filter with a partial flow of filtered fluid opposite to the flow direction during filtration is backwashed, are movable. During this backwashing process, the partial flow of filtered fluid then dissolves the contaminants accumulated on the filter surface and, opposite to the flow direction of the fluid during filtration, delivers it to the atmosphere via a suitable valve upstream of the filter, so that after completion of this backwashing process, a contaminant is released Filter for the re-filtration is provided again.

In principle, the filter device according to the invention can be configured as is known, in which case, for example, the bandpass filters described in the prior art can be designated. However, it is particularly suitable if the filter device according to the invention is designed such that it has at least two filters arranged at an axial distance from one another within a bolt mounted in a housing and axially displaceable for this purpose. Optionally, the at least two filters can then be flowed through with the fluid to be filtered or at least one filter is flowed through by the fluid to be filtered, while at the same time the at least one other filter is in a position outside the housing, so that this one, outside the housing located Fil¬ ter manually replaced by the respective operating personnel and cleaned or replaced and replaced by a new filter er¬ can be.

Another, likewise advantageous embodiment of the inventive filter device comprises two, within a Ge housing arranged and axially displaceable for this purpose bolts, which are each provided with at least two, with axial distance from one another an¬ arranged filter. In this case, these bolts are mounted in corresponding housing bores fluid-tight and axially displaceable bar, wherein optionally all filters are flowed through by the fluid to be filtered or at least one filter is in a position outside the housing, while the remaining other filter of the filtered Flow through the fluid. This ensures that without interrupting the filtration process, one or more filters located or located in a position outside the housing can be exchanged or cleaned, without resulting in an undesirable pressure fluctuation.

Advantageous developments of the inventive method as well as the device according to the invention and the filter device according to the invention are specified in the subclaims.

The method according to the invention will be explained in more detail below with reference to two exemplary embodiments in conjunction with the drawing. Show it:

FIG. 1 shows a schematic perspective view of the filter device according to the invention,

FIG. 2 as in FIG. 1, but partly with a housing portion broken out, FIG. 3 as in FIG. 1, but partly with another larger housing area broken away, FIG.

FIG. 4 shows a schematic sectional view of a throttle, the throttle element being depicted in its second position (opened),

FIG. 5 as in FIG. 4, but in a partially opened position of the throttle element, and FIG

Figure 6 as Figure 4, but in a closed position of the throttle element.

In FIGS. 1 to 6, the same parts are provided with the same reference numerals.

The embodiment shown in FIGS. 1 to 3 of the filter device denoted overall by 1 has a fluid supply channel 3, whereby this fluid supply channel 3 extends from a first connection element 2 to a first filter 8 or 8a and a second filter 9 or 9a (FIGS. 2 and 3). Furthermore, the filter device 1 is provided with a housing 10 which comprises two mutually parallel bores 12 and 13, the two parallel aligned bolts 6 and 7 store fluid-tight and axially displaceable. In this case, each bolt is provided with at least two filters 8 or 8a and 9 or 9a arranged at an axial distance from each other, the respective second filter 8a and 9a being indicated schematically only as a filter 8a in FIG. As seen in the flow direction 16 of the fluid to be filtered, the filters are adjoined by a fluid discharge channel (not shown), this fluid discharge channel being connected to a tool, not shown, via a second connecting element (not shown). Both the fluid supply channel and the fluid discharge channel have a channel division, as can be seen for the fluid supply channel 3 in FIG. 2 with FIGS. 3a and 3b. This ensures that the Filter 8, 8a, 9 and 9a are supplied evenly with the fluid to be filtered.

The filter device 1 is further assigned a detection device 11, which is indicated only schematically in FIGS. 1 to 3. This detection device 11 is associated with two pressure sensors 14 and 15, wherein the pressure sensor 14 upstream of a throttle 5 and the pressure sensor 15 downstream of the filter 8, 8a, 9 and 9a in the fluid discharge channel (not shown) posi¬ tioned.

A throttle 5 provided in the fluid supply channel has a throttle element 4 which can be displaced axially relative to the flow direction of the fluid in the fluid supply channel, wherein FIGS. 2 and 3 reflect different positions of the throttle element 4. The receiving space 17 of the throttle element 4 is formed in the embodiment of the throttle 5 shown in Figures 1 to 3 by a portion of the fluid supply channel 3.

As can be seen in particular Figures 2 and 3, the throttle element 4 is designed as a cylindrical throttle element and has a diameter in its diameter to the inner cross section of the fluid supply channel 3 adapted passage opening 18 (Figure 2 and 3), so that by an axial displacement of Drosselelemen¬ tes 4 relative to the receiving space 17, the opening degree of the throttle is arbitrarily changeable.

The filter device 1 is connected via the first connecting element 2, for example with an extruder, not shown, and via the second connecting element with a tool, also not shown.

The above filter device 1 operates as follows:

First, the fluid to be filtered is supplied in the direction of arrow 16 via the fluid supply channel 3 to the two filters 8 and 9, filtered there and then passes as a filtered fluid through the adjoining fluid discharge channel to the not darge presented tool. At this time, a differential pressure is measured via the two Meß¬ sensors 14 and 15, wherein the size of this differential pressure via the throttle 5 is adjustable. At the beginning of this filtration is the axially displaceable throttle element 4 of the throttle 5 in a position as spielsweise in the figure 2 is shown and which was referred to above as the first position of the throttle element 4, ie in this position, the throttle almost completely the fluid flow, due to the fact that the overlap region zwi¬ tween the passage opening 18 and the cross section of the Fluidzu- driving channel 3 about 2% to 15%, preferably 5% to 10%, the total cross-section.

As a result of the throttling described above, a pressure of the fluid to be filtered, which is generally designated beforehand as the actual value of the working parameter of the fluid, is set on the measuring sensor 14. Furthermore, a further pressure is measured at the sensor 15, wherein the differential pressure detected from the two pressures is then compared in the detection device 11 with a predetermined differential pressure desired value.

As soon as the available filters 8 and 9 (FIG. 2) are covered with contaminants in the course of filtration, the differential pressure actual value changes, with the result that a deviation from the desired differential pressure value occurs here. which in turn leads to the detection device 11 generating an actuating variable, so that the throttle element 4 is displaced axially below the overall cross-section by enlargement. In this way, the backpressure caused by the throttle is reduced, with the extent of this reduction being directly proportional to the back pressure of the dirty filters 8 and 9. This process of continuously balancing and compensating the negative pressure of the contaminated filters by the constantly reducing back pressure of the throttle causes a constant pressure in the System. However, as soon as the throttle element has reached a second position, in which the throttle element is shortly before its voll¬ permanent opening, an acoustic and / or optical signal is generated, so that a filter change can be initiated. For this purpose, one of the two bolts moves into a position, as shown in FIG. 3, in which the filter 8 is arranged outside the housing of the filter device 1. At the same time, the throttle element 4 is moved so far axially downwards that the passage opening 18 over the entire surface with the cross section of the fluid supply channel 3 and thus the Dros¬ selelement does not hinder the fluid flow, which is referred to above as the second position. This coordinated axial displacement of the bolt and the throttle element acts to maintain the constant pressure in the fluid flow.

After replacement of the dirty filter 8, this is again transferred to a position in which it is arranged in the fluid flow, while at the same time the throttle element is displaced axially upward, whereby a reduction in the degree of opening of the throttle is brought about. Here, the extent of the axial Ver¬ shift of the throttle element 4 is controlled by the detection unit such that a constant pressure value is set by the comparison of the differential pressure actual value already described many times with the differential pressure target value.

The filter 9 or the filters 8a and 9a (the latter not shown) can be exchanged in an analogous manner, with the bolts 8 or the bolt 9 being displaced axially to the right for replacement of the filters 8a and 9a until they are positioned outside the housing of the filter device 1.

The throttle 5 shown further in FIGS. 4 to 6 differs in the throttle previously described in connection with FIGS. 1 to 3 in that the throttle according to FIGS. 4 to 6 is configured differently. The throttle 5 depicted in FIGS. 4 to 6 has a conically shaped throttle element 4, which is arranged within a conically shaped receiving space 17, wherein the FIG. 4 shows the throttle element 4 in its maximum opening position, FIG Throttle element 4 in its central opening position and the figure 6 shows the throttle element 4 in a closed position senen.

The throttle 5 is flowed through in the flow direction 16 by the fluid. In this case, the throttle 5 has a fluid supply sub-channel 19 arranged upstream of the throttle element 4, which on the one hand is connected to the (not shown) fluid supply channel 3 and which, on the other hand, opens into the receiving space 17. Downstream of the throttle element 4, in the open position of the throttle element, as shown in FIGS. 4 and 5, the fluid is guided laterally past the throttling element 4 between the outer wall of the conical throttle element 4 and the inner wall of the receiving space 17 then into a fluid discharge part passage 20, wherein a first portion 21 of the Fluidab- supply part channel is formed as an annular space. Due to the fact that the annulus is configured asymmetrically and has a continuosly tapered region, as indicated on the right side in FIGS. 4 to 6, the flow conditions in the annulus can be optimally configured by means of a throttle formed in this way. so that unwanted dead zones are avoided here.

The operation of the throttle shown in Figures 4 to 6 corresponds to the throttle, as described above in connection with Figures 1 to 3.

Should it be necessary, the throttle 5 described above in connection with FIGS. 4 to 6 can also be flowed through by the fluid in the opposite direction to the direction of the arrow 16, without this causing the previously described function of FIG

Throttle 5 changes.

Claims

claims

1. A method for filtering a fluid, in particular for filtering a polymeric melt, in which a pressurized stream of the fluid is continuously passed through at least one filter and thereafter the thus filtered fluid is supplied to a tool, characterized in that the flow of the fluid to be filtered and / or the filtered fluid is throttled, that at least one actual value of a working parameter of the fluid is measured, that the actual value is compared with a predefinable target value, which is dependent on at least one actual value. Setpoint value deviation at least one manipulated variable is generated and that depending on this manipulated variable, the degree of throttling ver¬ changes.

2. A process for filtering a fluid, in particular for filtering a polymeric melt, in which a pressurized stream of the fluid is continuously passed through at least one filter and thereafter the thus filtered fluid is supplied to a tool, characterized in that the flow of the fluid to be filtered and / or the filtered fluid is throttled, that at least one actual value of the degree of throttling is set, that at least one actual value of a working parameter of the fluid is measured and that the actual value of the degree The throttling is changed until the actual value of the working parameter of the fluid adopts a definable and constant desired value.

3. The method according to claim 1 or 2, characterized in that the actual value of the working parameter of the fluid, the pressure, the flow rate, the flow rate, the temperature and / or the viscosity of the fluid to be filtered and / or the filtered fluid is measured.

4. The method according to claim 1 or 3, characterized in that the flow of the fluid to be filtered is throttled.

5. The method according to claim 1 or 3, characterized in that the flow of the filtered fluid is throttled.

6. The method according to any one of claims 1 or 3 to 5, characterized in that the pressure of the fluid to be filtered is measured Senes that when exceeding a predetermined pressure value, the degree of throttling is reduced and that at Unterschrei¬ th a predetermined pressure value of Degree of throttling er¬ is increased.

7. The method according to any one of claims 1 or 3 to 6, characterized in that the pressure of the fluid is measured upstream and downstream of the throttling and that upon reaching a Grenz¬ value, a signal for carrying out a filter change er¬ testifies.

8. An apparatus for carrying out the method according to any one of the preceding claims, wherein the device comprises means, in particular an extruder, for generating a kontinuierli¬ chen flow of a pressurized fluid, in particular a polymeric melt, and a hereinafter arranged filter device with at least one Filter for filtering the fluid and a tool provided thereafter, characterized in that the region upstream and / or downstream of the filter device (1) is associated with a detection device (11, 14, 15) for the actual value of a working parameter of the fluid Furthermore, a throttle (5) is provided upstream and / or downstream of the filter device (1) in the flow of the fluid, and in that the detection device (11, 14, 15) controls a setting of the actual value from a predefinable desired value ¬ size for changing the opening degree of the throttle (5) generated in such a way that with increasing contamination use of the at least one Filters (8, 8a, 9) of the opening degree of the throttle (5) is continuously increased.

9. Apparatus according to claim 8, characterized in that the detection device is designed such that the Erfas¬ sung device (11, 14, 15) as the actual value of the working parameter of the fluid pressure, the flow rate, the Durchflußgeschwin¬ speed, the temperature and / or the viscosity of the fluid er¬ sums.

10. Apparatus according to claim 9, characterized in that the detection device (11, 14, 15) each have a pressure sensor

(14, 15) for detecting the fluid pressure upstream and / or downstream of the filter device (1) or for detecting the differential pressure, that the thus detected pressure actual value or differential pressure actual value with the predetermined pressure target Value or differential pressure setpoint value is compared and that the opening degree of the throttle (5) is increased as soon as the actual pressure value exceeds the desired pressure value.

11. Device according to one of claims 8 to 10, characterized ge indicates that the detection device (11) each have a temperature sensor for detecting the fluid temperature upstream and / or downstream of the filter device (1) or for detecting a differential temperature that the so detected Temperature actual value is compared with the predetermined temperature setpoint value and that the degree of opening of the throttle (5) is increased as soon as the actual temperature value exceeds the temperature setpoint value.

12. Device according to one of claims 8 to 11, characterized ge indicates that the throttle (5) upstream of the filter device

(1) is arranged.

13. The apparatus according to claim 12, characterized in that the throttle (5) is associated with a valve which, in its ge opened position, a fluid flow to the atmosphere derived.

14. Device according to one of claims 8 to 11, characterized ge indicates that the throttle (5) downstream of the filter device

(1) is arranged.

15. Device according to one of claims 8 to 14, characterized ge indicates that the throttle (5) has a fluid flowing through the receiving space (17) for a penetrating into the fluid Drosselele¬ element (4) and that the throttle element between a he ¬ sten position in which the fluid flow is almost interrupted, and a second position in which the fluid flow through the throttle element (4) is not or almost not hindered, and vice versa, is movable.

16. The apparatus according to claim 15, characterized in that the throttle element (4) as a cylindrical throttle piston and the receiving space (17) are formed as a cylindrical receiving space, wherein the cylindrical throttle piston in the cylindrical receiving space axially between the first position and the second position is displaceable ,

17. Device according to one of claims 8 to 15, characterized ge indicates that the receiving space (17) as a conical Aufnahme¬ space and the throttle element (4) are designed as a conical throttle element, that the conical throttle element (4) between the first position and the second position is axially displaceable and that the receiving space upstream of the throttle element (4) arranged fluid supply sub-channel (19) and a downstream of the

Throttle element provided Fluidabfuhrteilkanal (19) are zugeord¬ net.

18. The apparatus according to claim 17, characterized in that the fluid removal part channel (20) in the flow direction (16) Seen the fluid first section (21) which extends beidsei¬ tig of the housing of the receiving space (17) and which opens into the fluid discharge part channel (20).

19. The apparatus according to claim 18, characterized in that the first portion (21) of the Fluidabfuhrteilkanals (20) is designed as an annular channel, wherein the annular channel partially or completely, the housing of the receiving space (17).

20. Device according to one of claims 8 to 19, characterized ge indicates that, depending on the manipulated variable generated, the throttle element (4) is moved.

21. The apparatus according to claim 20, characterized in that the throttle element (4) is moved only over a predetermined size, said predetermined size between the first and second position of the throttle element (4), and that when exceeding this predetermined size, an optical and / or an acoustic signal is generated.

22. The apparatus of claim 20 or 21, characterized gekennzeich¬ net that when exceeding the predetermined size Rückspü¬ len of a dirty filter (8, 8a, 9) is automatically triggered.

23. Device according to one of claims 8 to 22, characterized ge indicates that the device comprises a filter device (1) um¬ inside a in a housing (10) mounted and axially displaceable bolt (6, 7) with two axial Ab¬ stood apart from each other filters (8, 8a, 9), wherein optionally both filters (8, 9) are flowed through with the fluid to be filtered or a filter is flowed through with the fluid to be filtered, while at the same time the other filter in a position outside the housing (10) of the Filter¬ device (1) is located.

24. Device according to one of claims 8 to 22, characterized ge indicates that the device comprises a filter device (1) um¬, the at least two, within a housing (10) arranged and axially displaceable thereto bolts (6, 7) ¬ each having at least two, with axial distance von¬ arranged filters (8, 8a, 9) are provided, wherein optionally all filters are flowed through with the fluid to be filtered or at least one filter in a position outside of the Housing (10) of the filter device (1) is located, while at the same time the other remaining filters are flowed through by the fluid to be filtered.

25. Filter device for carrying out the method according to one of the preceding claims 1 to 7 with a first Anschluß¬ element (2) for connecting the filter device (1) to a device for generating a continuous flow of a pressurized fluid and a second connecting element for connection the filter device (1) with a tool, wherein the filter device (1) has at least one filter through which fluid flows, characterized in that between the first connection element (2) and the filter (8, 8a, 9) and / or between the filter (8, 8a, 9) and the second An¬ circuit element detecting means (11, 14, 15) for the actual value of a working parameter of the fluid is arranged that between the first connection element (2) and the filter and / or between the filter and the second connecting element further in the flow of fluid, a throttle (5) is provided and that the detecting means (11, 14, 15) at a r deviation of the actual value from a predefinable setpoint value a manipulated variable Ver¬ change of the opening degree of the throttle (5) is generated such that with increasing contamination of the at least one filter (8, 8a, 9), the opening degree of the throttle (5) is continuously increased ßert.

26. Filter device according to claim 25, characterized in that the detection device (11, 14, 15) formed in such a manner in that the detection device (11, 14, 15) detects as the actual value of the working parameter of the fluid the pressure, the flow rate, the flow rate, the temperature and / or the viscosity of the fluid.

27. Filter device according to claim 26, characterized in that the detection device (11, 14, 15) each have a Druck¬ measuring sensor (14, 15) between the first connection element (2) and the filter and / or between the filter and the second to ¬ conclusion element for detecting the fluid pressure upstream and / or downstream of the filter or for detecting the differential pressure auf¬ has, that the thus detected pressure actual value or differential pressure actual value with the predetermined pressure target value or Differenz¬ pressure target value is compared and that the opening degree of the throttle (5) is increased as soon as the actual pressure value exceeds the desired pressure value.

28. Filter device according to one of claims 25 to 27, da¬ characterized in that the detection means (11, 14, 15) each have a temperature sensor between the first Anschluß¬ element and the filter and / or between the filter and the second connection element for detecting the fluid temperature strom¬ on and / or downstream of the filter or for detecting a Diffe¬ rence temperature that the thus detected actual temperature value is compared with the predetermined temperature target value and that the degree of opening of the throttle (5) is increased as soon as the actual temperature value exceeds the set temperature value.

29. Filter device according to one of claims 25 to 28, da¬ characterized in that the throttle (5) between the first connection element (2) and the filter (8, 8a, 9) is arranged.

30. Filter device according to claim 29, characterized in that the throttle (5) is associated with a valve which, in its ge opened position, a fluid flow to the atmosphere derived.

31. Filter device according to one of claims 25 to 30, da¬ characterized in that the throttle (5) between the filter (8, 8a, 9) and the second connection element is arranged.

32. Filter device according to one of claims 25 to 31, da¬ characterized in that the throttle (5) has a fluid durch¬ flowing through the receiving space (17) for a penetrating into the fluid throttle element (4) and that the throttle element (4). Between a first position in which the fluid flow is almost interrupted and a second position in which the fluid flow through the throttle element (4) is not or almost not obstructed, and vice versa, is movable.

33. Filter device according to claim 32, characterized in that the throttle element (4) as a cylindrical throttle piston and the receiving space (17) are formed as a cylindrical receiving space, wherein the cylindrical throttle piston in the cylindrical receiving space (17) axially between the first position and the second Position is displaced.

34. Filter device according to one of claims 25 to 32, da¬ characterized in that the receiving space (17) as a conical receiving space and the throttle element (4) are designed as conical throttle element, that the conical throttle element zwi¬ tween the first position and the second position is axially displaceable ver¬ and that the receiving space (17) upstream of the throttle element (4) arranged fluid supply sub-channel (19) and a downstream of the Drpsselelementes (4) provided Fluidabfuhr- partial channel (20) are assigned.

35. Filter device according to claim 34, characterized in that the fluid discharge part-channel (20) has a first section (21), viewed in the flow direction (16) of the fluid, which extends on both sides of the housing of the receiving space (17) and which is inserted into the fluid discharge sub-channel (20). opens.

36. Filter device according to claim 35, characterized in that the first portion (21) of the Fluidabfuhrteilkanals (20) is designed as an annular channel, wherein the annular channel partially or completely, the housing of the receiving space (17).

37. Filter device according to one of claims 25 to 36, da¬ characterized in that, depending on the manipulated variable generated, the throttle element (4) is moved.

38. Filter device according to claim 37, characterized in that the throttle element (4) is moved be¬ only over a predetermined size, said predetermined size between the first and second position of the throttle element (4), and that when exceeding this predetermined size an optical and / or acoustic signal is generated.

39. Filter device according to claim 37 or 38, characterized gekenn¬ characterized in that when exceeding the predetermined size, a backwashing of a dirty filter is automatically triggered.

40. Filter device according to one of claims 25 to 39, da¬ characterized in that the filter device (1) has a innen¬ half of a housing (10) mounted and axially verschiebba¬ ren for this purpose bolt (6, 7), with two with Axially spaced apart filters (8, 8a, 9) is provided, wherein optionally both filters with the fluid to be filtered durch¬ flows or a filter is flowed through with the fluid to be filtered, while at the same time, the other filter in a position outside of the Housing (10) of the filter device (1) is located.

41. Filter device according to one of claims 25 to 39, da¬ characterized in that the filter device (1) at least two, within a housing (10) arranged and axially displaceable thereto pin (6, 7), each with at least two axially spaced-apart filters (8, 8a,

9), wherein optionally all filters are traversed by the fluid to be filtered or at least one filter is located in a position outside the housing (10) of the filter device (1), while at the same time the other remaining filters from the to flowing through the filtering fluid.